Is CVE-2026-91181 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-91181?

CVE-2026-91181 has a CVSS v3 severity of MEDIUM (6.5).

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CVE-2026-91181

Description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 Fail to sanitize Team objects returned by the data retention teams endpoint which allows an authenticated user holding only the read-only Data Retention Policy permission to obtain a private team's secret invite_id and email, and use it to join the team without authorization, via GET /api/v4/data_retention/policies/{policy_id}/teams.. Mattermost Advisory ID: MMSA-2026-00702